Matrix Orbital LK202-25 Legacy User Manual

Page 17

Table 8: Connector Pinout

Pin 1

+5.0 VDC (+7 to +15 VDC with wide voltage option)

Pin 2

C SCL (clock)

Pin 3

C SDA (data)

Pin 4

Ground

2.2.4 ACK

The idea of ACK is to indicate when data has been received correctly. ACK does not check the validity

of the data. Clearly, this is of limited usefulness and even less so with Matrix Orbital modules. Matrix

Orbital modules are only capable of failing to acknowledge the bytes following the byte, which was not

received. To fully understand the reasons for this, one needs to understand something about how a Matrix

Orbital module processes data. Basically the reason why a Matrix Orbital module might fail to receive a byte

correctly is that it was unable to process the byte previous before the failed byte was transmitted. Because

the module cannot possibly know that it would be unable to store the byte before the next byte was received

it cannot know to not ACK. The reason for this situation in deference to situations one might be familiar

with (i.e., memory chips, etc) is that the Matrix Orbital module employs a microprocessor to perform these

data storage functions. A memory chip takes care of these things entirely within hardware subsystems that

operate at the same speed as the transmission themselves.

The display uses a standard Phillips 7bit address as defined by Phillips. However, Matrix Orbital specifies

C address in 8bits. The 8th bit, least significant bit (LSB or Low Order Bit) of the 8bit address is a read /

write bit. If we take a standard Phillips 7bit address of 45hex this would be in binary 1000101. This is 7bits.

Matrix Orbital would describe the Phillips I

C address of 45hex as 8Ahex (shifted 1 bit to the left). The read

address would be 8Bhex.

For more information on Phillips I

C please visit;

2.2.5 Dallas 1-Wire Bridge

The display offers one Dallas 1-wire bridge. All three headers are connected to one communication line.

A maximum of 32 1-wire devices can be connected to the display at a time.

Matrix Orbital

LK202-25